Electric furnace.



W. F. MONABB. ELECTRIC FURNACE.

APPLICATION FILED SEPT. 15,1913.

1,100,191 Patented June 16, 1914.

, T T L WITNESSES INVENTOR mm! 1. KONAIBB, 01' PITTSBURGH, PENNSYLVANI A.

nnacmc mmica.

Specification of Letters Patent. Application m September 15, 1913. Serial No. maze.

Patented June 16, 1914.

metal bearing ubstances or from their ores,-

or for melting metals or other substances.

The object of the invention is to provide an electric furnace of simple design, which is highly eiiicient, wherein the heat is applied economically and without undue loss wherein the electric arc is generatqi out of direct contact with the material, thereby enabling the'material to be easily melted in case a freeze takes place and wherein the electrodesare readily ad ustable in various ways to regulate the temperature.

The invention comprises the construction andarrangement of parts hereinafter described and claimed.

In the drawings, which represent one embodiment of the invention, Figure 1 is a sectional elevation; Fig. 2 is a lan view, the furnace cover being remove and Fig. 3 is a detail elevation of the electrode supporting and adjusting means.

M The furnace comprises a body wall or stack 1 formed of fire brick or other suitable refractory material, and which, if desired, may be provided with a metal shell orjacket 2. Said body has a metal bottom or base 3, which may rest directly upon or be fixed to the floor-or suitable legs or supports, and which is provided with two or more electrode carrying ledges or shelves 4 hereinafter referred to. In the form shown the furnace is of trunnions 5 supported by uprights or pillars 6, although it may be fixed or stationary, if desired.

The upper portion of the furnace is hollow to provide a downwardly tapering or hoppershaped, crucible chamber 7 in which the material to be melted or treated is placed, and which may be closed by a suitable cover 8 applied to the top of the furnace.- Beneath the crucible chamber 7 is an arc chamber 9, the two chambers being separated by a wall 10, preferably formed by, or consisting of an inverted bowl shaped carbon or graphite crucible with its rim the tilting type, having shut off, or if, for

resting on an annular ledge 11 of the furnace wall and held in place thereon by a setting 12 of clay or refractory material applied after the crucible is laid in place. tap hole 13 leads out through the wall of the furnace just above the bottom setting 12, so it may be tapped without tilting, but it is also provided with a pouring o ening 14, so it may be emptied by tilting i desired.

The walls of the arc chamber 9 are lined, as at 15, with carbon or phite, in order to protect themfrom t e arc, and are pierced, as at 16, to provide holes or slots through which the electrodes 17 project into said chamber. Each electrode comprises a bar or rod of carbon, graphite or a composition thereof, mounted in an insulating rm 18 and having a current lead 19 connected to its outer end. The insulating ring 18 is preferably provided with a metal sleeve or jacket 20 and is held or clamped in a casing 21 having a swivel connection 21- to a screw 22 threaded into a frame 23. Casing 21 slides vertically in ways 24 in frame 23 and may be adjusted to different heights orlevels therein by turning the screw 22. Frame 23 is mounted to slidetoward and from the furnace on ways 25 on the edge or shelf 4 and may be adjusted thereon by a feed screw 26 having an operating handle 27.

In use of the furnace the charge of material to be melted or treated is placed in the crucible 7. The cover is applied and the current turned on and an arc is produced between the two electrodes. The length and intensity of this arc may be adjusted by turning either or both of the screws 26 and varying the distance between the electrodes. These screws also 'ena'ble the arc to be kept central under the crucible 10 and the electrodes to be fed in as they are consumed. By adjusting the vertical screws 22 the electrodes may be moved nearer to or farther from the crucible bottom and the heat applied in the most effective manner.

It will be observed that the arc is produced in chamber 9 outside of the crucible chamber 7 and below the same. sequently out of direct contact with the metal or other material being treated and produces no deleterious e ect thereon. Moreover, in case the current is accidently any other reason, the material solidifies or freezes, it can be again melted by merely starting up the current,

when an arc is immediately produced as before. This avoids the necessity of chipping or blasting out the solid charge, which is necessary in case of a freeze in the furnace where the electrodes are immersed into lie-distributed uniformly in all directions,

' and not confined to a limited portion of the 'bath or molten material. Also, the arc is below the level of the crucible bottom, so the heat rises and produces the maximum effect at .or near the bottom of the furnace where the molten metal collects. The latter is consequently kept very' fluid and is not liable to solidify or freeze during normal operation of the furnace.

When the melting or reducing operation is finished the charge is withdrawn, either through the tap hole 13, or by tilting and pouring the furnace.

The apparatus is simple and the cost of maintenance is low. When the crucible bottom 10 wears out or burns through it may be readily broken out or removed and a new crucible installed. The crucible bottom is formed of carbon or graphite, as stated, and consequently is a good conductor of heat. The temperature of the furnace is easily regulated and may be maintained practically uniform by proper manipulation of the electrodes. I

What I claim is:

1. An electric furnace, comprising a crucible having a bottom provided with an arched portion, a pair of electrodes. having their cooperating end portions lying beneath the arched portion of said crucible bottom, and electric connections for producing an are between said electrodes.

2. An electric furnace, comprising a crucible having its bottom convex upwardly, and means for producing an arc beneath said furnace bottom.

3. An electric furnace, comprising a body wall having a crucible chamber and an arc chamber therein, a wall separating said chambers, said wall being concave downwardly, and means forproducing an arc in said are chamber.

5. An electric furnace, comprising a cruci- "ble having its bottom concave downwardly to form an arc chamber, a pair of electrodes having their cooperating end portions lying beneath said crucible bottom, andmeans for gdjusting said electrodes in said are chain- 6. An electric furnace, comprising a crucible having an arched bottom forming an arc chamber therebeneath, a pair of electrodes having their end portion in said are chamber, and means for adjusting said electrodes with reference to each other.

7 An electric furnace, comprising a crucible having its bottom concave downwardly to form an arc chamber, a pair of electrodes having their end portions lying. in said are chamber, and means for varying the distance between said electrodes and crucible.

8. An electric furnace, comprising a crucible having its bottom concave downwardly to form an arc chamber, a air of electrodes having their end portions ying in said are chamber, and means for varying the distance between said electrodes and the'distance between said crucible and electrodes.

9. An electric furnace; comprising a body wall having an inner chamber provided with a bottom ledge, an inverted crucible having its rim resting on said ledge, and a pair of electrodes having their cooperating end po1'- P tions located beneath said crucible.

10. An electric furnace, comprising a body I wall having. an inner chamber provided with a bottom ledge, an inverted crucible having its rim resting on said ledge, a pair of electrodes having their cooperating end portions located beneath said crucible, and means for adjusting said electrodes with reference to said crucible. A

In testimony whereof, I have hereunto set my hand.

WILLIAM F. MoNABB.

Witnesses:

ELBERT L. HYDE, G. B. SANDERSON. 

